Asynchronous Completion Token An Object Behavioral Pattern for Efficient Asynchronous Event Handling

Contemporary applications must respond to many types of events, ranging from user interface notifications to network messages. Delay-sensitive applications, such as network management systems, often perform long-runningoperations asynchronously to avoid blocking the processing of other pending events. When these asynchronous operations complete, applications may need more information than simply the notification itself to properly handle the event. This paper describes the Asynchronous Completion Token pattern, which allows applications to efficiently associate state with the completion of asynchronous operations.